penile plethysmograph (PPG)

"A prisoner should not be compelled
to stimulate himself sexually in order for the government to get a sense
of his current proclivities." --U.S. 9th Circuit Court of Appeals Judge
John Noonan

The penile plethysmograph (pluh-THIZ-muh-graf) (PPG) is a machine for measuring changes in the circumference
of the penis. A stretchable band with mercury in it is fitted around the subject's penis.
The band is connected to a machine with a video screen and data recorder. Any changes in
penis size, even those not felt by the subject, are recorded while the subject views
sexually suggestive or pornographic pictures, slides, or movies, or listens to audio tapes
with descriptions of such things as children being molested. Computer software is used to
develop graphs showing "the degree of arousal to each stimulus." The machine
cost about $8,000 when first developed in Czechoslovakia to prevent draft dodgers from
claiming they were gay just to avoid military duty. Farrall Instruments
Inc., of Grand Island, Nebraska, manufactures the device and in 1993 had
sold most of the 400 units then in use in sex-offender treatment centers in
some 40 states. Medical Monitoring Systems of New Jersey is also one of the
leading PPG manufacturers. Another vendor of the PPG is Behavioral
Technology Inc. in Salt Lake City. In addition to the United States, the
device is being used in China, Hong Kong, Norway, Britain, Brazil and Spain.

The theory behind the device is described by Dr. Eugenia Gullick

The plethysmograph . . . directly measures the outside evidence of sexual arousal.
We know-- it's established throughout the literature that when a man becomes sexually
aroused--there is engorgement of the penis. It's a one-to-one relationship.

In a polygraph, galvanic skin responses are measured, and we have to make a leap of
logic to think that galvanic skin response is related to anxiety, and therefore
truthfulness. And it is that jump in logic that leads to a lack of reliability at times
with that instrument . . . .

We know when the penis becomes engorged, we are measuring sexual arousal. So it's much
more akin to ... blood pressure measurement. (State of
North Carolina v. Robert Earl Spencer, 1995)

This much everyone seems to agree on: the device measures penile engorgement. Any male
who has awakened with an erection knows, however, that penile engorgement is not always a
measure of sexual arousal or sexual desire. On the other hand, most males would probably acknowledge that
penile engorgement occurring while watching pornographic movies is due to sexual arousal.

What utility could such a device possibly have? Two
uses have already been mentioned: to weed out false gays and to treat
sex-offenders. The latter is sometimes done in conjunction with aversion therapy, which
involves subjecting patients to electric shocks or foul odors while being shown sexually
suggestive pictures. The hope is that the treatment will dull the patient's interest in
sexy materials. The device can also be used in conjunction with cognitive
behavioral therapy in which the patient allegedly learns how to control his
responses to situations that might trigger sexual arousal or desire. Psychologists use the PPG to measure the success of the therapy.

Submission to a PPG has been made a condition of parole for
certain sex offenders. The PPG has been used in child-custody cases to determine that a
father is or is not likely to abuse his child, and in sentencing decisions for sex
offenders. It has even been given to children as young as 10 who had abused other
children. The latter was done in Phoenix, Arizona, with no evidence either that the test
was useful or that it would not be harmful when given to children. Not
everyone submits quietly to the PPG requirements, however. Officials in Old Town,
Maine, had to pay nearly a million dollars to a policeman who was threatened with firing
for refusing to submit to a PPG.

Despite the lack of a theoretical basis for
interpreting the data gathered using the PPG, Professor Henry E. Adams et
al. of
the University of Georgia used the PPG to measure arousal of heterosexual men
who were divided into homophobes and non-homophobes. They published their
results in the Journal of Abnormal Psychologyin 1996:

The results of this study indicate that individuals
who score in the homophobic range and admit negative affect toward
homosexuality demonstrate significant sexual arousal to male homosexual
erotic stimuli.*

In their study of 64 exclusively heterosexual men
(self-identified), 66 percent of the non-homophobic group showed no
significant arousal while watching a male homosexual video, while only 20
percent of the homophobic men showed little or no evidence of arousal.

Adams notes that there are at least two competing
explanations for the fact that homophobic men would be aroused by "male
homosexual erotic stimuli." One is the Freudian explanation in terms of
latent homosexuality. Despite their protests, these heterosexual homophobes
are secret homosexuals. Another explanation, however, is that

viewing homosexual stimuli causes negative emotions
such as anxiety in homophobic men but not in non-homophobic men. Because
anxiety has been shown to enhance arousal and erection, this theory would
predict increases in erection in homophobic men. Furthermore, it would
indicate that a response to homosexual stimuli is a function of the threat
condition rather than sexual arousal per se.

There may be other explanations, as well, but we have
no way at present to determine which, if any, are valid.

Also,

there is an area where this device makes a valuable contribution: that of sorting
out organic from psychogenic impotence. This is done by measuring changes in penile
circumference during sleep, with increases expected during REM sleep. Men with psychogenic
impotence still show erections, while those with an organic problem don't. It works. (Dave Bunnell,
personal correspondence, who says he once set up a lab in the psychiatry
department at the University of Pennsylvania to do this.)

Finally, there are some therapists who claim that
chemical castration will significantly reduce or eliminate sexual arousal
that leads to criminal behavior by sexual predators. However, clinical
psychologist Jesus Padilla, who works with sexual predators at
Atascadero State Hospital, "measured arousal rates of men who had been
chemically castrated against men who had not by using a device that shows
the men photographs of children and women in various nonsexual poses. He
found no difference in arousal rates between Atascadero patients who had
been castrated and those who had not" (Sacramento
Bee, Special Report on Sexual Predators, February 14, 2006). While
the Bee does not describe the device used in this test, it was
likely the plethysmograph. In 1996, California implemented a law that
keeps Sexually Violent Predators (SVPs) after they've served their
sentences. SVPs are those who are "deemed likely to commit sexually
violent acts in the future following completion of their prison
sentences." A treatment program for SVPs was instituted and part of the
treatment includes "a willingness to complete specific assessment
procedures such as a plethysmograph evaluation."*
[The state of California has not revealed much about this program, but
Mareva Brown and Sam Stanton of the Sacramento Bee did a detailed
investigative report on it. Part 1,
Feb. 12, 2006;
Part 2, Feb. 13;
Part 3, Feb. 14.]

where's the science?

Scientifically, what are we to make of such a device? Well, the machine can measure
response time to a stimulus and it can measure change in penile girth over time.
Apparently, it is assumed that the more quickly aroused and the greater the engorgement
the higher the "arousal level." Apparently, it is also assumed by many
practitioners that any "arousal level" when viewing or listening to descriptions
of naked children or adults having sex with children is "deviant." Yet,
according to studies
done by the inventor of the PPG,
Dr. Kurt Freund, "many so called normal men who have not
committed illegal sex acts show considerable arousal to stimuli depicting naked children
or children involved in sexual activity."* And, in one court case
(State of North Carolina v. Robert Earl Spencer, 1995),
Dr. William Michael Tyson, a clinical and forensic psychologist specializing in the field of
sexual criminal behavior, testified that "the vast majority of individuals who commit
sexual offenses against children are not sexually aroused by stimulus material involving
children." His expert adversary in that case, Dr. Gullick, claimed that "the
plethysmograph has been extensively studied and recently shown to be ninety-five percent
accurate in discriminating between individuals who had committed sexual offenses against
children and a control group that was randomly drawn from the population." Yet, other
experts have claimed that there are "studies in which the devices have failed to
detect nearly one out of three known sex offenders tested."

It seems to be the case that the device has been the subject of many scientific studies
and the results have been mixed, to put it kindly. The reliability and utility of the
device have been argued in court and penile plethysmographic evidence has been declared
inadmissible because of its "questionable reliability." The case in which Dr.
Tyson testified was heard by the North Carolina Court of Appeals. That Appeals Court
upheld a lower court's exclusion of testimony by Dr. Gullick because her testimony was
based on the use of the penile plethysmograph. The defendant in the case was accused of
sexually molesting his 5-year old stepdaughter. He called Dr. Gullick to testify that his
"arousal pattern" when tested on the plethysmograph indicated that he was not
aroused by children. Presumably, the defense believed that this was strong evidence that
he didn't molest the child. The trial court ruled that "Dr. Gullick would be
permitted to testify as to any opinions which were not based on the plethysmograph."
The Appeals Court agreed with the trial court that "the instrument was of
questionable reliability; that the testimony was not relevant; and that even if relevant,
its probative value was outweighed by its prejudicial effect."

We agree with the trial court that the evidence before it by no means established
the reliability of the plethysmograph; there is a substantial difference of opinion within
the scientific community regarding the plethysmograph's reliability to measure sexual
deviancy....

In the present case, plethysmograph testing formed the basis for Dr. Gullick's opinion
that defendant was not sexually aroused by children, thereby making it less likely that he
committed the acts charged. In view of the lack of general acceptance of the
plethysmograph's validity and utility and therefore, its reliability for forensic purposes
in the scientific community in which it is employed, we hold that the trial court did not
abuse its discretion in finding defendant's plethysmograph testing data insufficiently
reliable to provide a basis for the opinion testimony which defendant sought to elicit
from Dr. Gullick. (State of
North Carolina v. Robert Earl Spencer)

Dr. Tyson testified in the Spencer case that it was "generally accepted in the
mental health community by both proponents and opponents of the plethysmograph that the
plethysmograph data do not give any evidence that is useful in determining whether an
individual did or did not commit a specific act. He also noted that "there is
substantial disagreement as to the extent to which the penile response is subject to
voluntary control and as to whether the penile response as measured by the plethysmograph
can then be generalized to anything else pertaining to sexual behavior." Putting it
mildly, Dr. Tyson claims that the plethysmograph has very limited forensic utility. It
seems clear that evidence based on the PPG has no business in the courtroom, either to
exculpate or incriminate.

Nevertheless, there is a growing industry of therapists who treat sex offenders and think
the PPG will assist them "in determining whether someone who has committed a sex
crime has a pattern of deviant sexual interests." Therapists use the PPG to help them
devise treatment programs and to measure the success of their treatment. All this is done
without any concern, apparently, that there is no compelling evidence that sexual
arousal or non-arousal from pictures or sounds significantly correlates with criminal
deviant behavior. There is no compelling evidence that a person who gets aroused by
pictures or sounds is significantly more likely to commit sex crimes than one who does not
get aroused. On the other hand, there is no compelling evidence that a person who does not
get aroused by pictures or sounds is significantly less likely to commit sex
crimes than one who does get aroused.

Still, the PPG can provide some information which might prove useful to a sex-offender
therapist. The computer software used with the PPG enables the tester to develop graphs
that indicate whether the subject is more aroused by males than by females, by children
than by adults, by coerced than by consensual sex, etc. The therapeutic controversy
begins, however, as soon as the therapist tries to convert "arousal levels" to
anything meaningful, such as claims that a sex-offender is "cured" or is
"responding positively to treatment." This is in addition to the controversy
already mentioned over using the PPG in conjunction with aversion therapy or
cognitive/behavioral therapy.

One glaring problem with the use of the PPG is the lack of standardized materials to
use as stimuli for subjects, a factor that clearly biases the data. Therapists vary
greatly in the kind of materials they use to arouse subjects. Some materials are rather
tame, e.g., nude adults, children in underwear or bathing suits. Others use hardcore
pornography, including depictions of rape and pedophilia. Furthermore, there is no
standard of "deviancy" for arousal. Worse, if therapists can define certain
arousal as deviant, they can then suggest treatments for the deviancy as well as having
the power to declare when the "deviant" is "cured." Convicted
sex-offenders are in no position to protest either declarations that they have
"deviant arousals" or treatments forced on them in the name of curing them of
the "disease" of "deviant arousal."

More objectionable than the questionable scientific
validity of the device, however, are the moral and legal questions its use
raises. Some of the materials would probably be illegal on the open market
because they constitute child pornography. Much of the material is morally
objectionable. Some of the uses of the device raise constitutional issues.
For example, submission to the PPG test as a condition for employment, for
enlistment in the
armed forces, or for being granted custody of children. Some penal institutions have made
submission to the PPG a condition of parole, even though the device's usefulness as a
predictor of behavior is unproven. The practice has been upheld by the Seventh Circuit Court of
Appeals (1995). Parole Boards have great latitude in establishing conditions for parole.
These conditions do not have to meet the same rigorous standards as are required before
something allegedly scientific can be admitted as evidence in a trial. Nor do the normal
liberties and constitutional protections of citizenship automatically apply to one being
paroled.

From a scientific, moral, and legal point of view, what should matter is whether a
person gives in to perverse desires and commits sex crimes. It is neither
immoral nor a crime to get aroused. Furthermore, being aroused is not identical to having
a desire. A man or woman may be aroused by the sight of animals copulating or be aroused
by a film of a woman eating a banana and a man eating a fig in particularly provocative
ways. Still, they may have no desire to engage in bestiality or have sex with a bowl of
fruit or have sex at all. A heterosexual man or woman may be aroused by the sight of lesbians engaging in
oral sex but have no desire to have sex with lesbians or in the presence of lesbians.
And, if Dr. Tyson is correct, apparently there are many "normal" men who are
aroused by photos of naked children but have no desire to have sex with children.
There are many pedophiles who are not aroused by photos of naked children. The PPG
measures arousal, not desire, though many sex-offender therapists seem
to identify arousal with desire. These therapists, therefore, may be engaging in little
more than wishful thinking when they think that because they witness a decrease in arousal
they have evidence for a decrease in desire, which they correctly correlate with a
decreased likelihood of acting on that desire. Decreased arousal may not be strong
evidence for decreased tendency to engage in criminal sex acts. Strong arousal need not
imply strong desire for what causes the arousal; and weak arousal need not imply weak
desire. Furthermore, no test can determine whether a person will act on his feelings and
desires. Nevertheless, many of those who treat sex offenders swear by the PPG even though
there is no compelling evidence that PPG readings validly indicate a tendency to
commit or not commit sex crimes.

In case you are wondering, there is a similar device
for measuring female arousal. G. Sintchak and J. H. Geer created a
vaginal plethysmograph in 1975, but vaginal probing for signs of arousal
is no more reliable than penile measurements. There is no sound theoretical
basis for interpreting what the
measurements mean (Meston 2000). "A
vaginal
photoplethysmograph is more complicated, because it measures the amount
of blood in the genitalia by monitoring minor changes in skin color inside
the vagina. It is essentially similar to a lie detector that measures blush
response."*

Throwing Away the
Key: Is a lifetime in jail the best way to deal with sex offenders?
Sex-offender treatment strategies generally fall into two categories, says [Pamela]
Schultz, "behavioral treatments, which have to do with the physical
impulses [and] those that focus on what's above the neck." In the first
category, the aim is to "deaden the sexual impulse," either through
"chemical castration" with hormonal drugs such as Depo-Provera or through
exposure to unpleasant sensations—the smell of ammonia, for example—in
conjunction with sexually suggestive images. (Counselors test whether this
last treatment is working with a device called a penile plethysmograph,
which measures blood flow and arousal.) Literal castration is sometimes
used—it's popular in Texas—but as
Slate has noted, "even castrated men are often still able to maintain an
erection, and some castrated men have managed to reoffend."

Toronto: global epicenter for oppression of sex and gender minorities
One device used at the Centre for Addiction and Mental Health (CAMH,
formerly the Provincial Lunatic Asylum) is the penile plethysmograph. Though
most courts treat this plethysmograph like a polygraph and deem it
scientifically unreliable and inadmissible as evidence in criminal trials,
that hasn't stopped the CAMH people from using it to create evidence about
all kinds of sex and gender minorities.

NewOnce Ridiculed, Male Bisexuals Are for Real Researchers placed a penile plethysmograph -- a rubber band-shaped band -- on the base of men's penises while they watched videos of male to male and female to female sex. "We measured actual physical arousal," said Rosenthal. "You can't create arousal when it isn't there for them. You can't fake it."

(comment: True, but sexual arousal by something is not the same as a proclivity to, attraction to, or desire to engage in sex with that something.) [/new]

Czech "peter meter" test for gay asylum seekers slammed by EU "If you think a TSA grope is bad, gay men seeking asylum in the Czech Republic are forced to drop their pants and get hooked up to a penile plethysmograph to find out just how gay they are. After the "peter meter" device is attached to their penises, they are subjected to all kinds of pornography to see what happens to their junk. This test then determines if they can seek asylum."

B.C. suspends penile sex tests on young offenders "...the
B.C. Civil Liberties Association demanded the government
intervene after it learned of the tests. Within hours, the
government suspended the sex testing after the provincial
advocate for children and youth announced she would conduct a
review....During the test, a youth would attach a device to his
penis that is designed to measure his physical sexual arousal.
Researchers in another room then play images of adults having
sex, followed by images of naked children and infants, as they
monitor the youth's level of arousal...."